Operation ranch hand; 40 years on, the clean-up continues

A $43 million clean-up operation has begun in Vietnam to decontaminate the former US airbase in Da Nang of a chemical called TCDD (a nasty carcinogen often referred to as "dioxin").

The plan revolves around the excavation and thermal treatment of around 73,000 cubic metres of soil in a project which will take approximately four years.

The clean-up project stems mostly from the fallout from an American program of defoliation and crop destruction during the Vietnam War, known as Operation Ranch Hand.

Operation Ranch Hand may be the largest targeted defoliation in human history. Lasting almost nine years, it affected almost 20% of the surface area of South Vietnam - approximately 5 million acres of forest and jungle, and half a million acres of cropland. The operation also used an incredible amount of herbicide: around 72,000 cubic metres - equivalent to more than 25 Olympic swimming pools full of chemicals (and approximately the same as the volume of soil that needs to be treated at Da Nang alone).

Operation Ranch Hand made use of three different herbicide mixes - codenamed Agent Orange, Agent White and Agent Blue. The most commonly used, Agent Orange, was a mix of two chemical herbicides, but was found to contain significant concentrations of the highly toxic compound TCDD, owing to poorly temperature-controlled production of one of the ingredients.

It is widely suggested that TCDD can have significant health effects, including the promotion of growth of cancers and birth defects - although no conclusive scientific study has been conducted.

Fortunately, although we still use a chemical called Picloram, which was one of the constituents of Agent White, we now have decades of scientific and allegorical data to show that our herbicides pose no health risks when used correctly - other than to plants, of course...